Abstract
BACKGROUND The measurement of carbon isotopic discrimination in grape sugars at harvest (δ13 C) is an integrated assessment of water status during ripening. It is an efficient alternative to assess variability in the field and discriminate between management zones in precision viticulture, but further work is needed to completely understand the signal. RESULTS This work, spanning over 3 years, performed in a hillslope toposequence in Burgundy, delineates the relationships between main soil properties (gravel amount, slope, texture) and the grapevine water status assessed by δ13 C. The highest δ13 C, indicating most severe water deficit, was recorded in gravelly soils on steep slopes. The amount of sugars and malic and tartaric acids was also related to δ13 C. The relationship between δ13 C and predawn leaf water potentials (Ψpd ) was also investigated, because the absolute values of measured δ13 C were lower than the values currently found in the literature. CONCLUSIONS A mini-meta-analysis was performed, which showed that the slope of the relationships between minimum Ψpd and δ13 C was stable across studies (a change of 1‰ in δ13 C corresponded to a change of -0.2 MPa in the minimum Ψpd ), while the intercept of the comparison δ13 C/Ψpd changed, probably because of genetic variations between varieties, or environmental differences. © 2017 Society of Chemical Industry.
